Sensor Data Search System, Sensor Data Search Method and Management Computer

ABSTRACT

In the sensor data retrieval system, a gateway connected to a plurality of sensor devices collects sensor data including measurement values and time stamps and stores them in a temporary storage part, and the management computer collects sensor data and stores sensor data in the first storage part, the management computer updates the collected time for each gateway as the first time, registers the sensor data of the first storage part in the second storage part in the registration cycle, the search part which updates the latest time stamp among the time stamps of the registered sensor data for each gateway with the second time as the second time and accepts the search period and searches for the sensor data of the time stamp included in the search period, and the search upper limit time from the search period, and compares the second time with the search upper limit time.

CLAIM OF PRIORITY

The present application claims priority from Japanese patent applicationJP 2016-171672 filed on Sep. 2, 2016, the content of which is herebyincorporated by reference into this application.

BACKGROUND

The present invention relates to a computer system that collects andsearches for sensor data.

The main purpose of a conventional sensor data search system is to findnecessary data from long-term data (data collected one day to severalmonths before) accumulated throughout one day or one month to perform abusiness process or analysis on that data. However, as IoT (Internet ofThings) is more widely used, more and more businesses find valuable aservice that provides an added value by analyzing short-term datacollected more recently (less than a minute to several minutes ago) andperforming a feedback process in a shorter cycle, and there is a strongdemand for a technique that can rapidly find and process short-termdata.

In the conventional sensor data search system, a gateway that collectssensor data from a sensor device temporarily accumulates datatransmitted from the sensor device, and the accumulated sensor data issent to a sensor data management apparatus that stores the sensor dataat a certain time interval, thereby suppressing an increase in overheaddue to the header addition.

The sensor data management apparatus stores a certain amount of datareceived from the gateway in a buffer, and registers the data indatabase in bulk, thereby reducing the registration processing time forthe database.

Thus, the sensor data collected recently is saved in not the database ofthe sensor data management apparatus, but the buffer of the sensor datamanagement apparatus or the gateway, and therefore, it is necessary toperform a search process on not only the database, but also a pluralityof storage devices including the buffer of the sensor data managementapparatus and the gateway.

SUMMARY

An object of the present invention is to reduce the time required tofind the sensor data recently collected.

Japanese Patent Application Laid-open Publication No. H5-289921discloses a known example in which a search process is performed on notonly the database, but also the data that has not been registered(committed) in the database.

Japanese Patent No. 5111719 discloses, as a known example, a means tooutput data that combines a plurality of search results performed on aplurality of databases.

When those known examples are applied, whether the long-term data or theshort-term data is to be searched, a search process needs to beperformed on all of the storage devices. Thus, when the short-term datais to be analyzed in real-time in an order of several hundreds ms toseveral seconds, the search time of the short-term data would be toolong to achieve a desired analysis time.

A representative aspect of the present disclosure is as follows. Asensor data search system for searching sensor data, comprising: agateway connected to a plurality of sensor devices; and a managementcomputer including a processor and a memory, the management computerbeing connected to a plurality of the gateways, wherein the gateway isconfigured to collect sensor data from the sensor devices and store thesensor data in a temporary storage part, the sensor data including ameasurement value, a time stamp, and an identifier, wherein themanagement computer includes: a receiving part configured to collect thesensor data of each gateway, store the sensor data in a first storagepart, and update a first time, which is a time at which the sensor datawas collected, for each gateway; a data committing part configured toregister the sensor data of the first storage part into a second storagepart at a prescribed time interval of registration cycle, compare timestamps of the registered sensor data among the respective gateways, andupdate a second time to a value of the latest time stamp for eachgateway; and a search part configured to receive a search period, andsearch for sensor data including time stamps within the search period,and wherein the search part calculates a search upper limit time basedon the current time and the search period, and compares the second timewith the search upper limit time.

According to the present invention, it is possible to limit storageparts to be searched based on the most recent time stamp and the searchperiod of the sensor data registered in a database of the sensor datamanagement apparatus, and if the search period is short, the searchscope of the sensor data can be made smaller, which makes it possible tospeed up the search process.

The problems, configurations, and effects other than those describedabove will be apparent by the descriptions of embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of the configuration of asensor data search system according to an embodiment of presentinvention.

FIG. 2 is a block diagram showing a specific example of the sensor datasearch system according to the embodiment of present invention.

FIG. 3A is a block diagram showing an example of the configuration ofthe sensor data management apparatus according to the embodiment ofpresent invention.

FIG. 3B is a block diagram showing an example of the gateway accordingto the embodiment of present invention.

FIG. 3C is a diagram showing an example of the current time tableaccording to the embodiment of present invention.

FIG. 3D is a diagram showing an example of the alert related sensordevice information table according to the embodiment of presentinvention.

FIG. 3E is a diagram showing an example of the asset information tableaccording to the embodiment of present invention.

FIG. 3F is a diagram showing an example of the gateway packettransmission time table according to the embodiment of presentinvention.

FIG. 3G is a diagram showing an example of the most recent time tableaccording to the embodiment of present invention.

FIG. 3H is a diagram showing an example of the sensor data informationtable

FIG. 4 is a block diagram showing an example of the configuration of thesensor data management apparatus according to the embodiment of presentinvention.

FIG. 5 is a block diagram showing an example of the hardwareconfiguration of the gateway according to the embodiment of presentinvention.

FIG. 6 shows a time chart showing an example of the sensor datacollection in the sensor data search system according to the embodimentof present invention.

FIG. 7 is a flowchart showing an example of the process to send thesensor data to the sensor data management apparatus from the gatewayaccording to the embodiment of present invention.

FIG. 8 is a flowchart showing an example of the process of the sensordata management apparatus according to the embodiment of presentinvention.

FIG. 9 is a flowchart showing an example of the process for the sensordata management apparatus to register all of the sensor data accordingto the embodiment of present invention.

FIG. 10 is a flowchart showing an example of the data bulk registrationprocess in the data committing part according to the embodiment ofpresent invention.

FIG. 11 is a diagram for explaining an example in which the sensor datamanagement apparatus searches for the sensor data according to theembodiment of present invention.

FIG. 12A is a flowcharts showing an example of the first half of processconducted by the search part of the sensor data management apparatusaccording to the embodiment of present invention.

FIG. 12B is a flowcharts showing an example of the second half ofprocess conducted by the search part of the sensor data managementapparatus according to the embodiment of present invention.

FIG. 13A is a diagram for explaining the patterns of the areas to besearched according to the embodiment of present invention.

FIG. 13B is a diagram for explaining the patterns of the areas to besearched according to the embodiment of present invention.

FIG. 13C is a diagram for explaining another patterns of area to besearched according to the embodiment of present invention.

FIG. 14A is a diagram showing an example of the effects according to theembodiment of present invention.

FIG. 14B is a diagram showing an example of the effects according to theembodiment of present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, embodiments of a sensor data search system of the presentinvention will be explained with reference to appended figures.

<System Configuration Diagram>

FIG. 1 is a block diagram showing an example of the configuration of asensor data search system of the present invention. The sensor datasearch system 1 includes a sensor data management apparatus 10, aplurality of gateways 20-1 to 20-N, and a system management server 40,and collects sensor data 3001 from a plurality of sensor devices 30-1 to30-m. In the descriptions below, the constituting elements arecollectively denoted with a reference character without a suffix, andwhen an individual element needs to be identified, a suffix is added tothe reference character with a hyphen.

The sensor device 30 is a sensing device such as a temperature sensor,humidity sensor, and vibration sensor, and sends out a measured value,as sensor data 3001, to the network at a certain time interval. Thesensor device 30 has the clock function indicating the current time, andadds the measured time to the sensor data 3001. The sensor device 30also has the function of sending an alert that notifies an abnormalcondition (or signs of abnormality). The abnormal condition is a statewhere the measured value of the sensor device 30 and the like meetprescribed conditions. The alert can be notified to the sensor datamanagement apparatus 10 by including a certain message in the sensordata 3001.

The gateway 20 receives the sensor data 3001 from the sensor device 30,temporarily stores the sensor data in a sensor data temporary storagepart 202, combines a plurality of pieces of sensor data 3001 stored inthe sensor data temporary storage part 202 into a packet 2001 at acertain time interval, and sends the packet 2001 to the sensor datamanagement apparatus 10.

The sensor data management apparatus 10 receives the packet 2001 fromthe gateway 20, and retrieves the plurality of pieces of sensor data3001 from the payload of the packet 2001. The sensor data managementapparatus 10 stores the sensor data 3001 in a first storage part 102,which functions as a buffer, for a prescribed period of time, andregisters a plurality of pieces of sensor data 3001 stored in the firststorage part 102 into a second storage part 104, which functions as adatabase, at a certain time interval.

The system management server 40 is a server that provides anadministrator of the sensor data search system 1 with a screen interfaceto search for the sensor data 3001 collected by the sensor data searchsystem 1, a screen interface to configure the sensor data search system1, and the like.

The sensor data 3001 sent from the sensor device 30 is stored in one ofthe sensor data temporary storage part 202 of the gateway 20, the firststorage part 102 of the sensor data management apparatus 10, and thesecond storage part 104 of the sensor data management apparatus 10, andthe storage location changes as time goes by.

FIG. 2 is a block diagram showing a specific example of the sensor datasearch system 1 of the present invention. FIG. 2 shows an example of thesensor data search system 1 that manages piping in a site like a factoryas a specific example.

Temperature sensors 30-1 to 30-3, humidity sensors 30-4 to 30-6, andvibration sensors 30-7 to 30-9 are installed on piping 50, and anadministrator detects abnormality of the pipe based on the measuredvalues of temperature, humidity, and vibration (acceleration).

The respective sensors 30 are connected to different gateway devices20-1 to 20-N, and in the example of FIG. 2, the temperature sensors 30-1to 30-3 are connected to the first gateway 20-1, the humidity sensors30-4 to 30-6 are connected to the second gateway 20-2, and the vibrationsensors 30-7 to 30-9 are connected to the N-th gateway 20-N.

The sensor data management apparatus 10 and the respective gateways 20are connected to each other via a network 4, and the respective gateways20 and the sensor devices 30 are connected to each other via networks5-1 to 5-3, respectively. The system management server 40 may also beconnected to the network 4.

FIG. 3A is a block diagram showing an example of the configuration ofthe sensor data management apparatus 10 of the present invention. Thesensor data management apparatus 10 includes a packet receiving part101, a first storage part 102, which is a buffer, a data committing part103, a second storage part 104, which is a database, a gateway packettransmission time recording part 105 configured to record the time atwhich a packet was sent from a gateway, a most recent time recordingpart 106, a search part 107, a current time memory 108, an alert relatedsensor device information memory 109, and an asset information memory110.

The packet receiving part 101 has the function of receiving a packet2001 sent from the gateway 20, and includes a header informationobtaining part 1011 that reads out header information of the receivedpacket 2001, a gateway packet transmission time obtaining part 1012 thatobtains the time at which the gateway 20 sent the packet 2001 from theheader information and that records the time in the packet transmissiontime recording part 105 for the gateway 20, and a buffer allocation part1013 that stores a plurality of pieces of sensor data 3001 obtained fromthe payload of the received packet 2001.

The first storage part 102 is a buffer to temporarily store theplurality of pieces of sensor data 3001 stored in the payload of thereceived packet 2001. The first storage part 102 includes N-number ofbuffers 1021-1 to 1021-N, N being the number of connected gateways 20.For example, the sensor data 3001 included in the payload of the packet2001 received from the first gateway 20-1 is stored in the first gatewaybuffer 1021-1.

The data committing part 103 has the function of registering all of theplurality of pieces of sensor data 3001 stored in the first storage part102 in the second storage part 104, which is the database, and includesa buffer data obtaining part 1031 that obtains the sensor data 3001 fromthe first storage part 102, a data format converting part 1032 thatconverts the sensor data 3001 to the format necessary for the data to beregistered in the database, a data bulk registration part 1033 thatregisters a plurality of pieces of sensor data 3001 together in thesecond storage part 104, which is the database, a time stamp obtainingpart management computer that obtains the time stamp of the sensor data3001, a most recent time calculation part management computer thatcalculates the most recent time that indicates the most recent timestamp among the sensor data 3001 registered in the second storage part104, a most recent time obtaining part 1036 that reads out the mostrecent time recorded in the most recent time recording part 106, and adata bulk registration timer 1037 that determines the time at which thedata bulk registration is performed.

The second storage part 104 is the database for storing the sensor data3001, and has a sensor data information table 1041 (see FIG. 3H). InFIG. 3H, the sensor data information table 1041 has several fields suchas a time stamp F11 indicating the time at which the sensor data 3001was measured, a sensor device ID (F12) that stores an identifier of thesensor device 30, an item F13 indicating the measurement item such as atemperature and humidity, and a measured value F14.

The gateway packet transmission time recording part 105 is a functionpart that holds the transmission time T_transmit of the last packet sentby the gateway 20, and has a gateway packet transmission time table 1051(see FIG. 3F). In FIG. 3F, the gateway packet transmission time table1051 has, as the fields thereof, a gateway ID (F21) and a packettransmission time T-transmit (F22), and stores the information of thepacket transmission time for each gateway 20.

The most recent time recording part 106 is a function part that storesthe most recent time indicating the latest time stamp among the sensordata 3001 registered in the second storage part 104, and has a mostrecent time table 1061 (see FIG. 3G). In FIG. 3G, the most recent timetable 1061 has, as the fields thereof, a gateway ID (F31) and a mostrecent time T_recent (F32), and stores information of the most recenttime for each gateway 20.

The search part 107 has the function of searching for the sensor data3001. The administrator of the sensor data search system 1 enters thesearch conditions of the sensor data 3001 through the input function ofthe system management server 40, thereby causing the search part 107 tosearch for the sensor data 3001.

The current time memory 108 has the clock function of storing thecurrent time T_current 1081 (see FIG. 3C).

The alert related sensor device information storage part 109 storesinformation of the sensor data 3001 that needs to be referred to whenthe sensor device 30 issues an alert, in order to analyze the situationindicated by the alert, and has an alert related sensor deviceinformation table (alert related information) 1091 (see FIG. 3D).

In FIG. 3D, the alert related sensor device information table 1091 is atable indicating the sensor device IDs related to the sensor device 30that has issued the alert, and the search target time period of thesensor data 3001 necessary to analyze the alert.

In FIG. 3D, the alert related sensor device information table 1091 has,as the fields thereof, an alert originating device ID (F41) indicatingthe sensor device ID that has issued the alert, a related sensor deviceID list F42 indicating IDs of sensor devices that transmits the sensordata related to the alert of the alert originating sensor device 30, anda related time range F43 indicating the target time period of the sensordata 3001 to be searched for, which is necessary for analyzing the alertof the sensor device A.

The administrator of the sensor data search system 1 determinesinformation to be stored in the alert related sensor device informationtable 1091 in advance, and enters the determined information in thealert related sensor device information table 1091 through the inputfunction of the system management server 40.

The asset information storage part 110 is a function part that storesthe information of the gateway 20 connected to each sensor device 30,and has an asset information table 1101 (see FIG. 3E). In FIG. 3E, theasset information table 1101 has, as the fields thereof, a device ID(F51) and a connected gateway ID (F52) indicating the gateway IDconnected to the sensor device 30.

FIG. 3B is a block diagram showing an example of the gateway 20. Thegateways 20-1 to 20-3 have a configuration similar to that of FIG. 3B.The gateway 20 has a sensor data receiving part 201, a sensor datatemporary storage part 202, a sensor data obtaining part 203, atransmission header creating part 204, a current time memory 205, and asensor data transmission part 206.

The sensor data receiving part 201 includes the function of receivingthe sensor data 3001 sent from the sensor device 30 through the network5, and storing the sensor data 3001 in the sensor data temporary storagepart 202.

The sensor data temporary storage part 202 is a buffer that temporarilystores the sensor data 3001. The sensor data obtaining part 203 storesthe accumulated plurality of pieces of sensor data 3001 as the payloadof the packet 2001.

The transmission header creating part 204 generates a transmissionheader of the packet 2001. The gateway ID and the packet transmissiontime are included in the transmission header. The current time memory205 has the clock function of keeping the current time, and thetransmission header creating part 204 includes the time indicated by thecurrent time memory 205 in the transmission header as the packettransmission time.

The sensor data transmission part 206 sends the generated packet 2001through the network 4 to the sensor data management apparatus 10.

<Explanation of Time Managed by Sensor Data Management Apparatus>

In order to narrow down the scope of the storage parts to be searchedfor (sensor data temporary storage part 202 of the gateway 20, the firststorage part 102, and the second storage part 104), the sensor datamanagement apparatus 10 keeps three kinds of time, which are the currenttime T-current, the packet transmission time T_transmit indicating thetime at which the last packet was sent by the gateway 20, and the mostrecent time T_recent indicating the latest time stamp among the sensordata 3001 registered in the second storage part 104. The packettransmission time T_transmit and the most recent time T_recent are keptseparately for each gateway 20.

<Hardware Configuration Diagram>

FIG. 4 is a block diagram showing an example of the configuration of thesensor data management apparatus 10 of the present invention. The sensordata management apparatus 10 includes a processor 501, a memory 502, astorage device 506, a gateway interface 503, a server interface 504, anda bus 505. The processor 501, the memory 502, the storage device 506,the gateway interface 503, and the server interface 504 are connectedvia the bus 505.

The processor 501 performs processes corresponding to the functionprogram 601 loaded to the memory 502. The function program 601 includesa packet receiving program 6101 executing the processes of the packetreceiving part 101, a data committing program 6103 executing theprocesses of the data committing part 103, and a search program 6107executing the processes of the search part 107.

The memory 502 includes the first storage part 102 is comprised of aplurality of gateway buffers 1021-1 to 1021-N. The current time memory108 is loaded to the memory 502, thereby allowing the processor 501 tohave the clock function of keeping the current time T_current 1081 (seeFIG. 3C).

The respective function parts of the packet receiving part 101, the datacommitting part 103, and the search part 107 shown in FIG. 3A are loadedto the memory 502 as the search program 6107.

The processor 501 operates in accordance with a program of each functionpart, thereby operating as a function part that realizes a prescribedfunction. For example, the processor 501 functions as the search part107 by performing the processes in accordance with the search program6107. The same applies to other programs. The processor 501 alsooperates as a function part that realizes each function of a pluralityof processes conducted by respective programs. The computer andcomputing system are a device and system that include those functionparts.

Information for realizing the respective functions of the functionprogram 601 such as programs and tables can be stored in the storagedevice 506, a memory device such as a non-volatile semiconductor memory,hard disk drive, or SSD (solid state drive), or a computer readablenon-temporary data storage medium such an IC card, SD card, or DVD.

The storage device 506 stores therein data to be referred to when thefunction program 601 is executed. The storage device 506 includes thesecond storage part 104 comprising the sensor data information table1041, the gateway packet transmission time recording part 105 that hasthe gateway packet transmission time table 1051, the most recent timerecording part 106 comprising the most recent time table 1061, the alertrelated sensor device information memory 109 comprising the alertrelated sensor device information table 1091, and the asset informationmemory 110 comprising the asset information table 1101.

The gateway interface 503 inputs and outputs communication data to andfrom the gateway 20. The server interface 504 inputs and outputscommunication data to and from the system management server 40.

In the example of the figure, the gateway buffer 1021 was disposed onthe memory 502, but the gateway buffer 1021 may alternatively bedisposed on the storage device 506.

FIG. 5 is a block diagram showing an example of the hardwareconfiguration of the gateway 20 of the present invention. The gateway 20includes a processor 701, a memory 702, a local area network interface703, and a wide area network interface 704, and a bus 705. The processor701, the memory 702, the local area network interface 703, the wide areanetwork interface 704, and the storage device 706 are connected via thebus 705.

The processor 701 performs processes corresponding to a function program801. The function program 801 includes a sensor data receiving partprogram 8201 executing the processes of the sensor data receiving part201, a sensor data obtaining part program 8203 executing the processesof the sensor data obtaining part 203, and a transmission headercreating part program 8204 executing the processes of the transmissionheader creating part 204.

The respective function parts of the sensor data receiving part 201, thesensor data obtaining part 203, and the transmission header creatingpart 204 shown in FIG. 3B are loaded to the memory 702 as the sensordata receiving part program 8201, the sensor data obtaining part program8203, and the transmission header creating part program 8204.

The processor 701 operates in accordance with a program of each functionpart, thereby operating as a function part that realizes a prescribedfunction. For example, the processor 701 functions as the sensor datareceiving part 201 by performing the processes in accordance with thesensor data receiving part program 8201. The same applies to otherprograms. The processor 701 also operates as a function part thatrealizes each function of a plurality of processes conducted byrespective programs. The computer and computing system are a device andsystem that include those function parts.

Information for realizing the respective functions of the functionprogram 801 such as programs and tables can be stored in the storagedevice 706, a memory device such as a non-volatile semiconductor memory,hard disk drive, or SSD (solid state drive), or a computer readablenon-temporary data storage medium such an IC card, SD card, or DVD.

The storage device 706 stores therein data to be referred to when thefunction program 801 is executed. The storage device 706 includes thesensor data temporary storage part 202 that functions as a buffer.

The sensor device 30 is connected to the local area network interface703, and the sensor data management apparatus 10 is connected to thewide area network interface 704 via the network 4.

<Sensor Data Collection Process>

FIG. 6 shows a time chart showing an example of the sensor datacollection in the sensor data search system 1 of the present invention.FIG. 6 shows an example in which the sensor data management apparatus 10collects the sensor data 3001 from the sensor device A30-1 and thesensor device B30-2 connected to the first gateway 20-1.

In FIG. 6, t_sA_n (n is a variable number) indicates the time at whichthe sensor device A30-1 sends the sensor data 3001, and t_sB_n (n is avariable number) indicates the time at which the sensor device B30-1sends the sensor data 3001.

t_G1_n (n is a variable number) indicates the time at which the firstgateway 20-1 sends the sensor data 3001, which was received from thesensor device 30-1 and the sensor device 30-2, to the sensor datamanagement apparatus 10.

t_DB_n (n is a variable number) indicates the time at which the sensordata management apparatus 10 registers the sensor data 3001 accumulatedin the first storage part 102 all together in the second storage part104. The value “n” is given to t_sA_n, t_sB_n, t_G1_n, and t_DB_n inseries, and the greater the value “n” is, the closer it is to thecurrent time.

The flow of the sensor data collection in the example of FIG. 6 will beexplained. The sensor device A30-1 and the sensor device B30-2respectively send the sensor data 3001 to the first gateway 20-1 inrespective transmission cycles T_A and T_B. The sensor data 3001includes a sensor device ID, a time stamp indicating the transmissiontime t_sA_n or t_sB_n of the sensor data 3001, and measured values ofthe sensor device.

The first gateway 20-1 stores a plurality of pieces of sensor data 3001,which are accumulated in the sensor data temporary storage part 202, inthe payload of the packet 2001, and sends the data to the sensor datamanagement apparatus 10 in a gateway transmission cycle T_gateway. Inthe header of the packet 2001, the gateway ID and the transmission timet_G1_n are included.

The sensor data management apparatus 10 receives the packet 2001 fromthe first gateway 20-1, obtains the transmission time t_G1_n from theheader of the packet 2001, and stores the transmission time as thepacket transmission time T_transmit of the first gateway 20-1. Thesensor data management apparatus 10 also obtains a plurality of piecesof sensor data 3001 from the payload of the packet 2001, and stores thedata in the first gateway buffer 1021-1 in the first storage part 102.

The sensor data management apparatus 10 registers the plurality ofpieces of sensor data 3001 accumulated in the first gateway buffer1021-1 of the first storage part 102 all together in the second storagepart 104 at a time interval of database bulk registration cycleT_database. In this bulk registration process, the sensor datamanagement apparatus 10 keeps, as the most recent time T_recent, thelatest time stamp among the time stamps of the sensor data 3001subjected to the bulk registration process.

For example, in FIG. 6, four pieces of sensor data 3001, which were sentfrom the sensor device A30-1, and three pieces of sensor data 3001,which were sent from the sensor device B30-2, are registered at the timet_DB_9. In this process, the latest time stamp is t_sB_6, and therefore,the sensor data management apparatus 10 keeps t_sB_6 as the most recenttime T_recent.

In the example of FIG. 6, at the time of t_DB_9, the sensor data 3001that had been sent from the sensor device 30 before t_DB_6 is stored inthe second storage part 104. The sensor data 3001 that had been sentfrom the sensor device after t_sB_6 and before t_G1_7 is stored in thefirst storage part 102. The sensor data 3001 sent by the sensor device30 after the time t_G1_7 is stored in the sensor data temporary storagepart 202 of the first gateway 20-1.

FIG. 6 shows the example of the “push” type where the packet 2001 issent by the first gateway 20-1 in a certain gateway transmission cycle,but the “pull” type may alternatively employed where the sensor datamanagement apparatus 10 sends a sensor data obtaining request to thefirst gateway 20-1 at a certain time interval, and obtains informationequivalent to the packet 2001.

The transmission cycle T_A of the sensor device A30-1, the transmissioncycle T_B of the sensor device B30-2, the gateway transmission cycleT_gateway, and the database bulk registration cycle T_database do nothave to be the same value, and may vary every time.

The example of the “push” type where the sensor data 3001 is sent by thesensor device 30 in a certain cycle T_A was shown, but the “pull” typemay alternatively be employed where the gateway 20 sends a sensor dataobtaining request to the sensor device 30 at a certain time interval,and obtains information equivalent to the sensor data 3001.

<Process of Sending Sensor Data to Sensor Data Management Apparatus fromGateway>

FIG. 7 is a flowchart showing an example of the process to send thesensor data to the sensor data management apparatus 10 from the gateway20. This process is conducted at a time interval of gateway transmissioncycle T_gateway shown in FIG. 6.

The sensor data obtaining part 203 of the gateway 20 obtains one or morepieces of sensor data 3001 from the sensor data temporary storage part202, and stores the data as the payload of a packet 2001 to be sent(Step S701).

Next, the transmission header creating part 204 of the gateway 20includes the gateway ID and the transmission time in the header of thepacket to be sent. The current time stored in the current time memory205 is included as the transmission time (Step S702).

Lastly, the sensor data transmission part 206 of the gateway 20 sendsout the packet 2001.

Through the process described above, the packet 2001 is sent from thegateway 20 to the sensor data management apparatus 10 at a time intervalof gateway transmission cycle T_gateway.

<Process of Receiving Sensor Data by Sensor Data Management Apparatus>

FIG. 8 is a flowchart showing an example of the process of the sensordata management apparatus 10 to receive the packet 2001 including thesensor data sent by the gateway 20. This process is conducted every timeafter receiving the packet 2001 from the gateway 20.

The packet receiving part 101 of the sensor data management apparatus 10receives the packet 2001 from the gateway 20 (Step S1201).

The header information obtaining part 1011 of the sensor data managementapparatus 10 obtains the gateway ID and the transmission time from thetransmission header of the received packet 2001 (Step S1202).

The gateway packet transmission time obtaining part 1012 of the sensordata management apparatus 10 refers to the gateway packet transmissiontime table 1051 stored in the gateway packet transmission time recordingpart 105, and updates the packet transmission time T_transmit (F22) ofthe entry with the sender gateway ID (F21) coinciding with the gatewayID obtained in Step S1202 to the time obtained in Step S1202 (StepS1203).

The buffer allocation part 1013 allocates the sensor data 3001 stored inthe payload of the received packet 2001 to the gateway buffer 1021 ofthe gateway ID obtained in S1202 (Step S1204).

Through the process described above, in the gateway packet transmissiontime table 1051, the transmission time of the packet 2001 is stored inthe packet transmission time T_transmit (F22) for each gateway 20, andthe sensor data 3001 is stored in the gateway buffer 1021 correspondingto the gateway ID.

<Process to Bulk-Register Sensor Data from Gateway Buffer into Databasein Sensor Data Management Apparatus>

FIG. 9 is a flowchart showing an example of the process for the sensordata management apparatus 10 to register all of the sensor data 3001,which is stored in the gateway buffer 1021, together in the secondstorage part 104 (database). This process is conducted at a timeinterval of database bulk registration cycle T_database shown in FIG. 6.

The data committing part 103 in the sensor data management apparatus 10configures the data bulk registration timer 1037 to the time until thedata bulk registration process is started (e.g., 30 minutes=T_database)(Step S901). After the configuring is done, the data bulk registrationtimer starts to count down.

The data committing part 103 checks if the time configured in the databulk registration timer has passed or not at a certain time interval(Step S902). If the time configured in the data bulk registration timerhas not passed (Step S902: NO), the data committing part 103 checks ifthe time configured in the data bulk registration timer has passed ornot again in a certain period of time (Step S902).

If the time configured in the data bulk registration time has passed(Step S902: YES), the data committing part 103 conducts the data bulkregistration process on N number of gateway buffers 1021 in anappropriate order. The data committing part 103 uses “x” as a variableto indicate the gateway ID subjected to the data bulk registrationprocess. The data committing part 103 initializes the value “x” atfirst, so that x equals 1 (Step S903). In Step S903, the data committingpart 103 conducts the data bulk registration process on the firstgateway buffer 1021-1 first.

The data committing part 103 conducts the data bulk registration processon the gateway buffer 1021-x with the gateway ID=x (Step S904). The databulk registration process will be described in detail below.

After the data bulk registration process is completed, the datacommitting part 103 adds 1 to the variable “x” indicating the gateway IDto be subjected to the data bulk registration process (Step S905). Thedata committing part 103 then determines whether the value “x” exceedsthe number (N) of gateway 20 or not (Step S906).

If the value “x” is equal to or smaller than the number N of the gateway20 (Step S906: YES), the data committing part 103 performs the data bulkregistration process on the gateway ID=x (Step S904).

On the other hand, if the value “x” is greater than the number N ofgateway 20 (Step S906: NO), this means that the data bulk registrationprocess has been performed on all of the N number of gateway buffers,and therefore, the data committing part 103 configures the data bulkregistration timer 1037 to the time until the bulk registration processis started (Step S901), and the processes of Step S902 to S906 will berepeated. The data bulk registration process will be repeated at such atime interval as configured in the data bulk registration timer 1037,and Steps S901 to S906 are repeated until the sensor data managementapparatus 10 is stopped.

The value of the time interval (T_database) of the bulk registrationprocess configured in the data bulk registration time 1037 may be afixed value that is registered in advance in the data committing part103 in the manufacturing process of the sensor data management apparatus10, or may be a variable that can be configured by the administrator ofthe sensor data search system 1 through the input function of the systemmanagement server 40. In this embodiment, the time interval ofperforming the data bulk registration process is the same among all ofthe gateway buffers 1021, but the data bulk registration timer 1037 maybe provided for each of the gateways 20, and the time interval ofperforming the data bulk registration process may be changed for each ofthe gateway buffers 1021.

For example, the time interval of the data bulk registration process ofthe first gateway buffer 1021-1 may be 30 minutes, and the time intervalof the data bulk registration process of the second gateway buffer1021-2 may be 45 minutes. In this case, the configuring value of thedata bulk registration timer of the first gateway is 30 minutes, and thesetting value of the data bulk registration timer of the first gatewayis 45 minutes.

<Data Bulk Registration Process at Data Committing Part>

FIG. 10 is a flowchart showing an example of the data bulk registrationprocess in the data committing part 103 shown in Step S904 of FIG. 9.The data committing part 103 enters the gateway ID=x (1≦x≦N) as theinput value of the data bulk registration process. This means that thedata bulk registration process is performed on the sensor data stored inthe x-th gateway buffer 1021-x (1≦x≦N).

First, the most recent time obtaining part 1036 of the data committingpart 103 refers to the most recent time table 1061 of the most recenttime recording part 106. Then, the most recent time obtaining part 1036obtains the most recent time T_recent (F32) of the entry including thegateway ID (F31) corresponding to the gateway ID=x. Lastly, the mostrecent time obtaining part 1036 stores the obtained value of the mostrecent time T_recent (F32) in the temporary variable T_temporary (StepS9041).

Next, the buffer data obtaining part 1031 obtains the sensor data 3001from the x-th gateway buffer 1021-x. The buffer data obtaining part 1031determines whether or not the sensor data 3001 is stored in the x-thgateway buffer 1021-x (Step S9042).

If the sensor data is stored (Step S9042: YES), the buffer dataobtaining part 1031 obtains one piece of the stored sensor data 3001(Step S9043).

The buffer data obtaining part 1031 enters the obtained sensor data intothe data format converting part 1032, and the data format convertingpart 1032 coverts the obtained sensor data 3001 from the binary formatto the data format required to be stored in the second storage part 104(database) (Step S9044). For example, the binary string constituting thesensor data 3001 is converted to a text string or value that makes senseto humans such as “time stamp=2020/1/1 11:55:00, Device ID=B,Item=Temperature, Value=28° C.”

The data format converting part 1032 enters the sensor data 3001, whichwas converted to the format to be registered in the second storage part104 (database), into the time stamp obtaining part 1034, and the timestamp obtaining part 1034 obtains the time stamp from the entered sensordata 3001, and enters the time stamp into the most recent timecalculating part management computer. The most recent time calculatingpart management computer determines whether the entered time stamp isafter T_temporary or not (Step S9045).

If the obtained time stamp is after T_temporary (Step S9045: YES), thedata format converting part 1032 updates the value of T_temporary to thetime of the obtained time stamp (Step S9046). If the obtained time stampis not after T_temporary (Step S9045: NO), the data format convertingpart 1032 does not update the value of T_temporary.

The data format converting part 1032 enters the sensor data 3001, whichwas converted to the format to be registered in the second storage part104 (database), into the data bulk registration part 1033, and the databulk registration part 1033 adds the entered sensor data to the databasebulk registration list (Step S9047).

As described above, the data committing part 103 repeatedly conducts theprocesses of Step S9043 to S9047 until the n-th gateway buffer 1021-x isempty (Step S9042: NO).

After the n-th gateway buffer 1021-x is empty (Step S9042: NO), the databulk registration part 1033 registers all of the data stored in thedatabase bulk registration list into the sensor data information table1041 of the second storage part 104 together (Step S9048). The bulkregistration into the sensor data information table 1041 may beperformed by the data bulk registration part 1033 in the chronologicalorder of the time stamps of the sensor data 3001.

Lastly, the most recent time calculating part management computer refersto the most recent time table 1061 of the most recent time recordingpart 106, and updates the most recent time T_recent (F32) of the entryincluding the gateway ID (F31) corresponding to the value of the gatewayID=x to the value of T_temporary (Step S9049), thereby completing thedata bulk registration process.

With the above-mentioned process, the sensor data 3001 of each gateway20 stored in the first storage part 102 is registered into the sensordata information table 1041 of the second storage part 104 in bulk at aprescribed time interval (database bulk registration cycle T_database).The sensor data management apparatus 10 configures the time stamp of themost recent value among the sensor data 3001 to be registered in bulk inthe most recent time table 1061 for each gateway 20 as the most recenttime (F32).

That is, the sensor data management apparatus 10 uses the gateway packettransmission time table 1051 to manage the recent time of the sensordata 3001 stored in the first storage part 102 (packet transmission timeof gateway 20) for each ID of gateway 20, and uses the most recent time(F32) of the most recent time table 1061 to manage the most recent timeof the sensor data 3001 registered in the sensor data information table1041 for each ID of gateway 20.

<Process to Search for Sensor Data Related to Alert Upon Detection ofAlert>

FIG. 11 is a diagram for explaining an example in which the sensor datamanagement apparatus 10 searches for the sensor data 3001 related to analert upon detection of the alert. FIG. 11 shows an example in which thesensor data management apparatus 10 detects an alert issued by thesensor device A30-1 in the example of the pipe management of FIG. 2.

The sensor data management apparatus 10 that has detected an alert fromthe sensor device A30-1 refers to the alert related sensor deviceinformation table 1091 in the alert related sensor device informationstorage part 109, and obtains two types of information using A, which isthe device ID of the sensor device A30-1 that has issued the alert, as akey. The two types of information are the related sensor device ID listF42 that indicates IDs of sensor devices that send out the sensor datarelated to the alert of the sensor device A (30-1), and the related timerange F43 (search period) that indicates the target time period of thesensor data necessary for analyzing the alert of the sensor device A.

In the example of FIG. 11, the administrator of the sensor data searchsystem 1 defines all sensor devices within a 500 meter radius from thesensor device A as the related sensor devices of the sensor device A,and enters six sensor device IDs of B, C, D, E, G, and H into therelated sensor device ID list F42 through the input function of thesystem management server 40. The related time range is configured by theadministrator of the sensor data search system 1 to 30 minutes inadvance, and the administrator enters 30 minutes in the relevant timerange F43 through the input function of the system management server 40.

The sensor data management apparatus 10 searches for the sensor data ofthe sensor devices B, C, D, E, G, and H during a time period of 30minutes prior to the current time based on the information obtained fromthe alert related sensor device information table 1091, and sends theobtained sensor data 3001 to the system management server 40. The systemmanagement server 40 uses the received sensor data 3001 to analyze thereason for the alert. FIG. 11 shows the example related to the sensordevice A (30-1), but the same applies to the other sensor devices 30,and by defining neighboring sensor devices 30 to analyze the sensor data3001 when a problem occurs in the alert related sensor deviceinformation table 1091 in advance, it is possible to immediately searchfor the sensor data 3001 of the neighboring sensor devices of the sensordevice 30 that has issued an alert. Also by configuring a time period toobtain the sensor data 3001 in the related time range F43 for eachsensor device 30, it is possible to appropriately analyze data dependingon the type and characteristics of the sensor device 30.

FIGS. 12A and 12B are flowcharts showing an example of the processconducted by the search part 107 of the sensor data management apparatus10 to search for related sensor data when an alert issued from thesensor device 30 is detected. First the search part 107 refers to thealert related sensor device information table 1091 in the alert relatedsensor device information storage part 109, and obtains the relatedsensor device ID list F42 and the related time range F43, using thesensor device ID of the sender of the alert as a key (Step S1201).

The search part 107 obtains the current time T_current from the currenttime memory 108 (1081), and calculates a related sensor data searchupper limit time T_past by subtracting the related time range, which wasobtained in Step S1201, from the current time T_current (Step S1202).The related sensor data search upper limit time T_past indicates the endof the search period going back from the current time T_current.

For example, if the current time T_current is 2020/1/1, 12:00:00, andthe related time range obtained in Step S1201 is 30 minutes, the relatedsensor data search upper limit time T_past is 2020/1/1, 11:30:00, andthe 30 minute period from 11:30:00 to 12:00:00 on 2020/1/1 is the searchtarget period of the sensor data 3001.

Next, the search part 107 searches for the sensor data 3001 of therelated sensor devices. The search part 107 determines whether thesensor data 3001 has been obtained for all of the sensor device IDs inthe related sensor device ID list F42 obtained in Step S1201 or not(Step S1203), and if there is a related sensor device which sensor datahas not been obtained (Step S1203: NO), the search part 107 selects thesensor device ID which sensor data has not been obtained from therelated sensor device ID list obtained in Step S1201 (Step S1204).

Next, the search part 107 identifies a gateway 20 connected to theselected sensor device 30. Specifically, the search part 107 refers tothe asset information table 1101 of the asset information storage part110, and obtains the connected gateway ID (F52) of the selected sensordevice ID using the sensor device ID selected in Step S1204 as a key(Step S1205).

Next, the search part 107 obtains the packet transmission time and themost recent time of the gateway 20 connected to the selected sensordevice 30. Specifically, the search part 107 refers to the gatewaypacket transmission time table 1051 of the gateway packet transmissiontime recording part 105, and obtains the packet transmission timeT_transmit (F22) of the connected gateway 20, using the connectedgateway ID obtained in Step S1205 as a key (Step S1206).

Then, the search part 107 refers to the most recent time table 1061 ofthe most recent time recording part 106, and obtains the most recenttime T_recent (F32) of the connected gateway 20, using the connectedgateway ID obtained in Step S1205 as a key (Step S1207).

Next, the search part 107 limits the search area (scope) using therelated sensor data search upper limit time T_past, the packettransmission time T_transmit of the connected gateway, and the mostrecent time T_recent of the connected gateway, and searches for thesensor data 3001 of the selected related sensor device ID list (F42).

Specifically, the search part 107 determines whether the related sensordata search upper limit time T_past is after the most recent timeT_recent or not (Step S1208).

If the related sensor data search upper limit time T_past is not afterthe most recent time T_recent (Step S1208: NO), the search part 107searches the first storage part 102 and the second storage part 104 ofthe sensor data management apparatus 10, and the sensor data temporarystorage part 202 of the gateway 20 connected to the related sensordevice, which was selected.

Next, the search part 107 searches the second storage part 104 (sensordata information table 1041) of the sensor data management apparatus 10for the sensor data 3001 of the related sensor device ID list (F42)after the time T_past (Step S1209), and searches the first storage part102 of the sensor data management apparatus 10 for the sensor data 3001of the related sensor device ID list (F42) by selecting the buffer 1021of the gateway ID obtained in Step S1205 (Step S1210). The search part107 also searches the sensor data temporary storage part 202 of thegateway ID obtained in Step S1205 for the sensor data 3001 of therelated sensor device ID list (F42) (Step S1211). The search target ofSteps S1209 to S1211 corresponds to FIG. 13A described below.

If the related sensor data search upper limit time T_past is after themost recent time T_recent (Step S1208: YES), the search part 107determines whether the related sensor data search upper limit timeT_past is after the packet transmission time T_transmit of the connectedgateway or not (Step S1212).

If the related sensor data search upper limit time T_past is not afterthe packet transmission time T_transmit of the connected gateway (StepS1212: NO), the search part 107 searches the first storage part 102 ofthe sensor data management apparatus 10, and the sensor data temporarystorage part 202 of the gateway 20 connected to the sensor device 30 ofthe related sensor device ID list (F42), which was selected.

The search part 107 searches the first storage part 102 of the sensordata management apparatus 10 for the sensor data 3001 of the relatedsensor device ID list (F42) after the time T_past from the buffer 1021corresponding to the gateway ID obtained in Step S1205 (Step S1213), andsearches the sensor data temporary part 202 of the gateway ID obtainedin Step S1205 for the related sensor data (Step S1214). The searchtarget of Steps S1213 to S1214 corresponds to FIG. 13B described below.

If the related sensor data search upper limit time T_past is after thepacket transmission time T_transmit of the connected gateway (StepS1212: YES), only the sensor data temporary storage part 202 of thegateway 20 connected to the selected sensor device 30 of the relatedsensor device ID list (F42) is to be searched, and the search part 107searches the sensor data temporary storage part 202 of the gateway IDobtained in Step S1205 for the sensor data 3001 of the related sensordevice ID list (F42) after the time T_past (Step S1215). The searchtarget of Step S1215 corresponds to FIG. 13C described below.

The sensor data search for the selected related sensor devices iscompleted as follows. After the sensor data search is completed for allof the related sensor devices (Step S1203: YES), the search part 107sends the sensor data, which was found in the search, to the systemmanagement server 40 (Step S1216).

FIGS. 13A to 13C are diagrams for explaining the patterns of the areasto be searched in the present invention. In FIGS. 13A o 13C, the sensordata 3001-1 to 3001-8 is stored in the second storage part 104 (sensordata information table 1041) of the sensor data management apparatus 10,the sensor data 3001-9 to 3001-15 is stored in the first storage part102 of the sensor data management apparatus 10 (buffer 1021), and thesensor data 3001-16 to 3001-22 is stored in the sensor data temporarystorage part 202 of the gateway 20.

The sensor data 3001-1 to 3001-22 in the diagrams is arranged in achronological order, where the sensor data 3001-1 is the oldest sensordata, and the sensor data 3001-22 is the latest sensor data.

As described in the flowchart of FIG. 12B, there are three patterns ofthe areas to be searched, which are determined based on the relatedsensor data search upper limit time T_past, the packet transmission timeT_transmit of the connected gateway, and the most recent time T_recentof the connected gateway. FIG. 13A shows an example in which the relatedsensor data search upper limit time T_past is not after the most recenttime T_recent (Step S1208 of the flowchart of FIG. 12B: NO).

In FIG. 13A, the first storage part 102 and the second storage part 104of the sensor data management apparatus 10 and the sensor data temporarystorage part 202 of the gateway 20 connected to the selected relatedsensor device are to be searched (Steps S1209, S1210, and S1211 of theflowchart of FIG. 12B), and the sensor data 3001-5 to 3001-22 is thesearch target.

FIG. 13B shows an example in which the related sensor data search upperlimit time T_past is after the most recent time T_recent (Step S1208 ofthe flowchart of FIG. 12B: YES), and the related sensor data searchupper limit time T_past is not after the packet transmission timeT_transmit of the connected gateway (Step S1212 of the flowchart of FIG.12B: NO).

In FIG. 13B, the first storage part 102 of the sensor data managementapparatus 10 and the sensor data temporary storage part 202 of thegateway 20 connected to the selected related sensor device are to besearched (Steps S1213 and S1214 of the flowchart of FIG. 12B), and thesensor data 3001-13 to 3001-22 is the search target.

FIG. 13C shows an example in which the related sensor data search upperlimit time T_past is after the packet transmission time T_transmit ofthe connected gateway (Step S1212 of the flowchart of FIG. 12B: YES).The sensor data temporary storage part 202 of the gateway 20 connectedto the selected related sensor device is to be searched (Step S1215 ofthe flowchart of FIG. 12B), and the sensor data 3001-19 to 3001-22 isthe search target.

FIGS. 14A and 14B are diagrams showing an example of the effects of theinvention. FIG. 14A shows the conditions defined to illustrate theeffects. 100 of gateways 20 are connected to the sensor data managementapparatus 10, and 100 of sensor devices 30 are connected to each gateway20.

Each sensor device 30 sends out sensor data 3001 every second. Eachgateway 20 sends out a packet 2001 every 10 minutes. The sensor datamanagement apparatus 10 performs bulk registration of the sensor datafrom the first storage part 102 to the second storage part 104 every 30minutes. The related device number of the alert issuing device (thenumber of sensors in the related sensor device ID list F42) is 100.

FIG. 14B is a graph that evaluates the sensor data search time of theconventional configuration and the present invention under theconditions of FIG. 14A. The search time when the data entry quantity is200,000 was configured to 0.01 seconds, and the search time wascalculated in a model where the search time is in proportion to the dataentry quantity.

The time required for the process of the present invention (theflowchart of FIGS. 12A and 12B) is 0.05 seconds when there are 100devices related to the alert originating device. The present inventionis effective when the sensor data is to be searched for up to fortyminutes immediately before the current time, and as compared with theconventional configuration, the search time can be reduced up to 1/500.

As described above, the sensor data management apparatus 10 manages themost recent time T_recent, which is the latest time stamp among the timestamps of the sensor data 3001 subjected to the bulk registration, foreach gateway 20, as well as the transmission time T_transmit of the lastpacket sent by the gateway 20 and the current time T_current.

The search part 107 of the sensor data management apparatus 10calculates the related sensor data search upper limit time T_past thatdetermines the search target, and narrows down the areas to be searched(memory area) by comparing the related sensor data search upper limittime T_past with the T_recent and T_transmit. In particular, bycomparing T_transmit with T_past (S1212), it is possible to determinewhether the search target can be narrowed down only to the gateway 20 ornot.

This way, the area (scope) of the memory to be searched for the sensordata 3001 can be kept to the minimum necessity, which speeds up thesearch process of the sensor data management apparatus 10 that handles alarge amount of data.

The sensor data management apparatus 10 has the related sensor device IDlist F42 that indicates sensor devices 30 to be analyzed when an alertfrom the sensor device 30 is detected, and therefore, it is possible toautomatically decide the sensor data 3001 to be collected upon detectionof an alert such as abnormality. As a result, an abnormal situation orfailure can be immediately handled.

In the embodiment described above, the sensor device 30 was configuredto send out one piece of sensor data 3001 at a time interval of theprescribed cycle T_A, but it is also possible that the sensor device 30sends out a plurality of pieces of sensor data 3001 at a time intervalof the prescribed cycle T_A.

This invention is not limited to the embodiments described above, andencompasses various modification examples. For instance, the embodimentsare described in detail for easier understanding of this invention, andthis invention is not limited to modes that have all of the describedcomponents. Some components of one embodiment can be replaced withcomponents of another embodiment, and components of one embodiment maybe added to components of another embodiment. In each embodiment, othercomponents may be added to, deleted from, or replace some components ofthe embodiment, and the addition, deletion, and the replacement may beapplied alone or in combination.

Some of all of the components, functions, processing units, andprocessing means described above may be implemented by hardware by, forexample, designing the components, the functions, and the like as anintegrated circuit. The components, functions, and the like describedabove may also be implemented by software by a processor interpretingand executing programs that implement their respective functions.Programs, tables, files, and other types of information for implementingthe functions can be put in a memory, in a storage apparatus such as ahard disk, or a solid state drive (SSD), or on a recording medium suchas an IC card, an SD card, or a DVD.

The control lines and information lines described are lines that aredeemed necessary for the description of this invention, and not all ofcontrol lines and information lines of a product are mentioned. Inactuality, it can be considered that almost all components are coupledto one another.

What is claimed is:
 1. A sensor data search system for searching sensordata, comprising: a gateway connected to a plurality of sensor devices;and a management computer including a processor and a memory, themanagement computer being connected to a plurality of the gateways,wherein the gateway is configured to collect sensor data from the sensordevices and store the sensor data in a temporary storage part, thesensor data including a measurement value, a time stamp, and anidentifier, wherein the management computer includes: a receiving partconfigured to collect the sensor data of each gateway, store the sensordata in a first storage part, and update a first time, which is a timeat which the sensor data was collected, for each gateway; a datacommitting part configured to register the sensor data of the firststorage part into a second storage part at a prescribed time interval ofregistration cycle, compare time stamps of the registered sensor dataamong the respective gateways, and update a second time to a value ofthe latest time stamp for each gateway; and a search part configured toreceive a search period, and search for sensor data including timestamps within the search period, and wherein the search part calculatesa search upper limit time based on the current time and the searchperiod, and compares the second time with the search upper limit time.2. The sensor data search system according to claim 1, wherein thesearch part is configured to compare the first time or the second timewith the search upper limit time, thereby narrowing down a scope of datastorage parts to be searched from the temporary storage part, the firststorage part, and the second storage part.
 3. The sensor data searchsystem according to claim 1, wherein, at a prescribed time interval oftransmission cycle, the gateway adds a transmission time to sensor datastored in the temporary storage part, and sends the sensor data to themanagement computer, and wherein the receiving part updates the firsttime to the transmission time for each gateway.
 4. The sensor datasearch system according to claim 1, wherein the first storage part has amemory area to store sensor data for each gateway, and wherein the datacommitting part obtains sensor data from each memory area of the firststorage part at a time interval of registration cycle, and registers allof the sensor data together into the second storage part in achronological order of the time stamp.
 5. The sensor data search systemaccording to claim 1, wherein the sensor device outputs an alertindicating an abnormal state, the alert including an identifier of thesensor device, wherein the management computer has alert relatedinformation including identifiers of search target sensor devicesrelated to the identifier of the sensor device that has issued thealert, and a search period, the identifiers of search target and thesearch period being configured in advance, and wherein, when receivingthe alert, the search part obtains identifiers of search target sensordevices corresponding to the identifier of the sensor device that hasissued the alert and the search period from the alert relatedinformation, and searches for sensor data of the search target sensordevices based on the search period.
 6. The sensor data search systemaccording to claim 1, wherein the management computer includes assetinformation in which a connection relationship between the sensordevices and the gateways is configured in advance, and wherein thesearch part refers to the asset information based on an identifier ofthe sensor device, and identifies a gateway connected to the sensordevice.
 7. A sensor data search method for searching sensor data,comprising: a first step in which a gateway connected to a plurality ofsensor devices collects sensor data including a measurement value and atime stamp from each of the sensor devices, and stores the sensor datain a temporary storage part; a second step in which a managementcomputer including a processor and a memory and being connected to aplurality of the gateways collects the sensor data for each gateway andstores the sensor data in a first storage part, and updates a first timeto the time at which the sensor data was collected for each gateway; athird step in which the management computer registers the sensor data ofthe first storage part into a second storage part at a prescribed timeinterval of registration cycle, compares time stamps of the registeredsensor data among the respective gateways, and updates a second time toa value of the latest time stamp for each gateway; and a fourth step inwhich the management computer receives a search period, and searches forsensor data including time stamps within the search period, wherein, inthe fourth step, a search upper limit time is calculated based on thecurrent time and the search period, and the second time is compared withthe search upper limit time.
 8. The sensor data search method accordingto claim 7, wherein, in the fourth step, the first time or the secondtime is compared with the search upper limit time, thereby narrowingdown a data storage part to be searched from the temporary storage part,the first storage part, and the second storage part.
 9. The sensor datasearch method according to claim 7, wherein, in the first step, at aprescribed time interval of transmission cycle, the gateway adds atransmission time to the sensor data stored in the temporary storagepart, and sends the sensor data to the management computer, and wherein,in the second step, the management computer updates the first time tothe transmission time for each gateway.
 10. The sensor data searchmethod according to claim 7, wherein the first storage part has a memoryarea to store sensor data for each gateway, and wherein, in the thirdstep, sensor data from each memory area of the first storage part isobtained at a time interval of registration cycle, and registered thesensor data in bulk into the second storage part in a chronologicalorder of the time stamp.
 11. The sensor data search method according toclaim 7, further comprising a step in which a sensor device outputs analert indicating an abnormal state, the alert including an identifier ofthe sensor device, wherein, in the fourth step, the management computerthat has received the alert refers to alert related information in whichidentifiers of search target sensor devices related to the identifier ofthe sensor device that has issued the alert and a search period areconfigured in advance, obtains identifiers of search target sensordevices corresponding to the identifier of the sensor device that hasissued the alert and the search period from the alert relatedinformation, and searches for sensor data of the search target sensordevices based on the search period.
 12. The sensor data search methodaccording to claim 7, wherein, in the fourth step, the managementcomputer refers to asset information in which a connection relationshipbetween the sensor devices and the gateways is configured in advance,and identifies the gateway corresponding to the identifier of the sensordevice.
 13. A management computer, comprising: a processor; and amemory, wherein the management computer is connected to a plurality ofgateways, and is configured to search for sensor data including ameasurement value, a time stamp, and an identifier of a sensor device,wherein the management computer further comprises: a receiving partconfigured to collect the sensor data for each gateway, store the sensordata in a first storage part, and update a first time, which is a timeat which the sensor data was collected, for each gateway; a datacommitting part configured to register the sensor data of the firststorage part into a second storage part at a prescribed time interval ofregistration cycle, compare time stamps of the registered sensor dataamong the respective gateways, and update a second time to a value ofthe latest time stamp for each gateway; and a search part configured toreceive a search period, and search for sensor data including timestamps within the search period, and wherein the search part calculatesa search upper limit time based on the current time and the searchperiod, and compares the second time with the search upper limit time.14. The management computer according to claim 13, wherein the searchpart compares the first time or the second time with the search upperlimit time, thereby narrowing down a data storage part to be searchedfrom the first storage part and the second storage part.
 15. Themanagement computer according to claim 13, wherein, at a prescribed timeinterval of transmission cycle, the receiving part receives a sensordata including a transmission time, and updates the first time to thetransmission time for each gateway.